1. Field of the Invention
The present invention relates to an endoscope apparatus and, more particularly, to an endoscope apparatus capable of displaying a blood vessel on an inside of a subject.
2. Description of the Related Art
Conventionally, in a medical field, minimally invasive various kinds of tests and operations have been performed using an endoscope. A surgeon can insert the endoscope into a body cavity, observe an image of an object picked up by an image pickup apparatus provided at a distal end portion of an endoscope insertion portion, and, according to necessity, apply treatment to a lesion site using a treatment instrument inserted through a treatment instrument channel. An operation performed using the endoscope has an advantage that a physical burden on a patient is small because laparotomy and the like are not performed.
An endoscope apparatus includes an endoscope, an image processing device connected to the endoscope, and an observation monitor. An image of a lesion site is picked up by an image pickup device provided at a distal end portion of an endoscope insertion portion. The image is displayed on the monitor. A surgeon can perform a diagnosis or necessary treatment while looking at the image displayed on the monitor.
With some endoscope apparatus, not only normal light observation performed using white light but also special light observation performed using special light such as infrared light can be performed in order to observe a blood vessel on an inside.
In the case of an infrared endoscope apparatus, for example, indocyanine green (ICG) having a characteristic of an absorption peak in near infrared ray near a wavelength of 805 nm is injected into blood of a patient as a drug. Infrared light near a wavelength of 805 nm and near 930 nm is irradiated on an object in time division manner from a light source device. A signal of an object image picked up by a CCD is inputted to a processor of the infrared endoscope apparatus. For example, as disclosed in Japanese Patent Application Laid-Open Publication No. 2000-41942, concerning such an infrared endoscope apparatus, as a processor, a device that allocates an image near a wavelength of 805 nm to a green signal (G), allocates an image near a wavelength of 930 nm to a blue signal (B), and outputs the signals to a monitor is proposed. Since the image of the infrared light near 805 nm often absorbed by the ICG is allocated to green, a surgeon can observe an infrared image during administration of the ICG at high contract.
For example, in endoscopic submucosal dissection (hereinafter referred to as ESD) or the like for dissecting and peeling off a submucosa, in which a lesion site is present, using an endoscope, not to cut a relatively thick blood vessel in a mucosa with an electric knife or the like, a surgeon checks a position of such a blood vessel and performs treatment such as dissection.